Professor Miller's lab primarily develops and applies laser diagnostics to the analysis of problems in combustion science, atmospheric chemistry, and biotechnology. In addition, we have published several papers in the field of the structure and optical properties of polynuclear aromatic hydrocarbons and their aggregates.

There are many
technologies available for measuring trace amount of gas species, but there are
tradeoffs between accuracy, sensitivity, selectivity, size and cost. For
example, while tunable diode laser absorption spectroscopy may provide
easily-interpreted spectrums for many gas species, this method generally can be
orders of magnitude less sensitive than laboratory equipment such as GC/MS. On
the other hand, while GC/MS is accurate, the equipment maybe too bulky, costly,
and unable to withstand vibration and shock in a field environment.

Therefore, for many
industrial applications, there is a need for a small sized field spectrometer
that can accurately measure trace species of sample gases at a reasonable cost,
equipment size, and power consumption.

GW researchers have
developed a compact cavity ring down spectrometer that can measure trace amount
of toxic gases at field environments. The spectrometer may use a tunable
solid-state continuous mid-infrared laser, which are sensitive to many gases.
An acousto-optic modulator, used as a “switch” for the laser, helps to
interrupt laser beam when resonance is achieved. A specially designed resonant
cavity may comprise of high-reflectivity mirrors in a bow-tie configuration. A
piezo-transducer drive modulator can be used to maintain resonance between
laser frequency and cavity modes, while a photo detector receives and generates
signals and measures an interaction between the laser beam and sample gas. Furthermore,
these researchers developed a method for extracting valuable data, filtering
out noise, and thus providing an accurate and timely reading.

This
spectrometer device can be uniquely compact and portable, and having a low power
consumption. The device can measure trace amount of
gaseous species such as HCHO, H2S, methy mercaptan, CO2,
CO, HCN, NH3, C2H2, sarin, VX, mustard gas,
arsine, phosgene, tear gas, pepper gas, nitrogen based explosives, and
incapacitating agents such as B2. Therefore, the spectrometer device can be installed
on aircraft, commercial building HVAC systems, public transportation systems,
for both accurate fire and toxic gas detection.

Researchers have patented various designs for this
novel spectrometer.

Applications:

Detecting
Trace Amount of Gases

Advantages:

Can
be used in field environments for continuous gas monitoring

Accurate,
sensitive to large species of toxic gases, and requires low power.